Use opam lock instead of custom opam repo
- Use opam lock (might need to be written by hand, but can be checked by currently released opam)
- Change the CI to only check this lock
- Deprecate the opam-repository and replace with a different docker-generating mechanism
- first stage of CI checks whether there is a docker image tagged with the hash of the opam.lock file
- if not make it
- second stage of CI (and further stages) simply uses the image
- first stage of CI checks whether there is a docker image tagged with the hash of the opam.lock file